Water Filters Information

Water filters accept liquids of poor or unknown purity and discharge a clear, clean output.

Operation

Water filters remove impurities through finely porous physical barriers and/or chemical and biological processes. Presented in the context of the food industry, this lecture illustrates.

Video credit: Layne Christensen Company

Types

Granularwater filters use sand, anthracite, garnet, or other media to remove impurities down to about 1 micron in size. Activated carbon (adsorption) and ion exchange (softening and deionization) techniques address chemicals/gases and dissolved inorganics respectively.

Membrane filters capture smaller than 1 micron particles through microfiltration, ultrafiltration, and nanofiltration. Reverse osmosis filters are slow, but can be 90-99% effective. Three general types of membranes are,

Depth which use absorption or entrapment

Screens use a set pore size to sort particulates

Surface membranes are made from multiple layers of media. When fluid passes through the filter, particles larger than the spaces within the filter matrix are retained.